Inorganic persalts and other percompounds giving hydrogen peroxide in solution, such as sodium perborate and sodium percarbonate, are widely used as a bleaching agent in detergent compositions. Other known percompounds liberating hydrogen peroxide in solution are e.g. the alkali metal persilicates and perphosphates and urea peroxide.
These persalts and percompounds provide a satisfactory bleach when the detergent composition is used at high temperatures, e.g. 80.degree.-100.degree. C., but they become less effective on lowering the wash temperature and are even ineffective when used at lower wash temperatures.
It is known that organic peracids, e.g. peracetic acid, are active at lower temperatures and the use of peracids in detergent compositions, either as such or formed in situ, has been suggested to give the detergent composition satisfactory bleaching properties at lower temperatures, e.g. in the 60.degree. C. wash cycle.
A considerable saving of energy would be obtained if washing habits could be further shifted towards cold and cool water washing, e.g. up to 40.degree. C., also for whites.
However, such detergent compositions do not have the ability to sufficiently suppress dye transfer when used for washing mixed and/or coloured loads.
It is an object of the present invention to provide an improved bleach system useful for the reduction of dye transfer in fabric washing.
It is another object of the invention to provide a washing composition suitable for washing coloured fabrics and mixed white and coloured fabrics at lower temperatures without substantial risk of dye transfer from one fabric to another. British Patent Specification No. 1 368 400 describes the activation of organic peracids by means of rather complex aldehyde or ketone compounds as the bleach activator. The use of a chloride salt (in fabric washing) and of a chloride or bromide salt (in hard surface bleaching) is described in conjunction with said activated peracid system. In the co-pending applications GB No. 79,28589 and GB No. 79,28590, filed Aug. 16, 1979, or U.S. Pat. No. 4,338,210 which resulted from an application claiming priority under the aforementioned British Patent Application No. 7,928,589 and U.S. Pat. No. 4,337,164 which resulted from an application which was a continuation-in part of an earlier application which derived priority from British Patent Application No. 7,928,590, bleach compositions are described comprising a peracid or a peracid precursor and a water-soluble bromide.